Biomedical subjects

J Jarchow

Publications and source records attributed to J Jarchow.

3 recordsLinked to original sources

PubMed1998

Species-specific association of the cell-aggregation molecule mediates recognition in marine sponges.

Reaggregation of dissociated cells of marine sponges, resulting in reformation of functional sponges, is a calcium-dependent process mediated by large, proteoglycan-like molecules termed aggregation factors (AF). During aggregation, species-specific sorting of cells is often observed. We purified and characterized AFs from three different sponge species and investigated their role in species-specific aggregation using novel approaches. The calcium-dependent association between purified AFs is species-specific in most combinations, as was shown in overlay assays and bead-sorting assays with AFs immobilized onto colored beads. Species-specific interactions of living cells and AF-beads resulted in incorporation of only homospecific AF-beads into reforming cell aggregates. Sequences from peptides obtained from the AF core proteins could all be aligned to the sequence of one species, the Microciona prolifera AFp3 core protein. In contrast to this similarity, major species-specific differences were seen in carbohydrate composition and in the response of AFs to specific carbohydrate-recognizing antibodies. In summary, our data point to a prominent role for the calcium-dependent association of AFs in recognition processes during aggregation. As this association of AFs occurs via carbohydrate-carbohydrate interactions, we speculate that the specificity of those interactions may be fundamental to recognition mechanisms required for regeneration of individuals from dissociated cells and for rejection of foreign material by sponge individuals.

Animals↗

PubMed1997

Probing single biomolecules with atomic force microscopy.

During the last years, atomic force microscopy (AFM) has developed from a microscopy tool for solid-state surface science toward a method employed in many scientific disciplines, such as biology, for investigating individual molecules on a nanometer scale. This article describes the current status of the imaging possibilities of AFM on RNA, IgG, and gold-labeled cell adhesion proteoglycans, as well as of measurements of intermolecular binding forces between biomolecules in order to investigate their molecular structure, function, and elasticity.

Animals↗

PubMedDate not supplied

Carbon release from purified chemoautotrophic bacterial symbionts of the hydrothermal vent tubeworm Riftia pachyptila.

The gutless hydrothermal tubeworm Riftia pachyptila Jones relies mainly on its chemoautotrophic bacterial symbionts to supply nutrients in the form of secreted organic compounds resulting from fixation and incorporation of CO2. In this study, symbionts were purified, tested for viability, and incubated in the presence of labeled CO2. We demonstrated that purified symbionts can be used as a viable alternative to experiments with bacterial cultures. Several organic acids, sugars, and amino acids were labeled, but their fraction of the total label stayed generally constant during the incubation times used. However, increasing fractions of succinate and, to a lesser degree, glutamate were excreted into the incubation medium, indicating that these are probably the main carbon-containing compounds transferred from the symbionts to the host. Glutamate could also account for the transport of nitrogen from the symbionts to the host.

Amino Acids↗